rebuild question

[carmiencke]

I have been thinkink about rebuilding the bottem end on my gs. It has over 200000 so i think its about time. My question is do i have to bore out the block or can i just replace the pistons. Any postive input appreciated.

 

[JusMX141]

Only your machine shop can tell you this, unless you pull the engine down yourself and take measurements at the bottom, middle, and top of the bore.

If the bores need straightened out, then yes you'll need to have the block bored and oversized pistons will need to be purchased.

DON'T buy the pistons without tearing the engine down first.

 

[caboose]

it depends if the cylinder walls have any damage, but a good hone will probably be a good idea, then check with a micrometer.

 

[LiquidX]

You will want to measure the bore to see if it's withing stock spec. If it's over, you'll bore it out the minimum amount and use the appropriate oversized piston. If it is within spec, you could just hone it and get stock bore pistons but if you want the best compression and clearance bore it out to eliminate any chance for warpage down the cylinder walls. Over time the walls will look like this \_/ but not exagerated out that far.

If you are really wondering, just drop the block and crank at the machine shop and have them measure out the bearing sizes and pistons needed.

 

[carmiencke]

Only your machine shop can tell you this, unless you pull the engine down yourself and take measurements at the bottom, middle, and top of the bore.

If the bores need straightened out, then yes you'll need to have the block bored and oversized pistons will need to be purchased.

DON'T buy the pistons without tearing the engine down first.

Alright thats what i sorta figured but wasnt too sure. Thank you.

 

[caboose]

if you have a cylinder bore micrometer you can do it yourself. but it sounds like you are going with the have the shop build the engine for me route.

 

[carmiencke]

if you have a cylinder bore micrometer you can do it yourself. but it sounds like you are going with the have the shop build the engine for me route.

No i will be buildin it but any machining i will most likely bring it to a shop.

 

[TastyTalon]

Agree. But the worst thing is to rebuild and have made an error of some sort in measuring. I'd probably take it to a shop and have them check it unless you are dead positive the cylinders walls are okay. Spend a few bucks now and prevent wasting a ton down the road.

 

[carmiencke]

Agree. But the worst thing is to rebuild and have made an error of some sort in measuring. I'd probably take it to a shop and have them check it unless you are dead positive the cylinders walls are okay. Spend a few bucks now and prevent wasting a ton down the road.

Thats what i was leaning towards. Also i was wondering if i do have to bore out the block and get oversized pistons what ones would be good to use with the stock rods.

 

[rhodess89]

yes you can take three measurements with a telescoping gauge, measure your reads from it and the it will let you know the taper of your bore in the block if not to wacked out the you can hone it and put stock size rings and pistons in it.

 

[carmiencke]

Alright what do people think of this build.
Npr pistons (turbo specs for compression)
clevite bearings
stock crank
14b turbo(10 to 15psi)
stock rods
ported exhaust mani and 02 sensor
aftermarket downpipe( not sure what brand yet)
cat back exhaust
intake (not sure what brand)
Most likely a front mount intercooler and hks bov
msd spark plug wires
e85
and at some point my cams regrinded to 272's
and all supporting mods. What kind power would i be looking at with this this set up considering its running right.

 

[carmiencke]

Any body?

 

[LiquidX]

Any body?

That wuold be classified under bench racing and it is not allowd on this forum.

Best I can say is look for the 14bs and see what hey do if they are around the same setup as you listet.
http://www.dsmtuners.com/forums/dynosheets.php
http://www.dsmtuners.com/forums/timeslips.php

 

[carmiencke]

That wuold be classified under bench racing and it is not allowd on this forum.

Best I can say is look for the 14bs and see what hey do if they are around the same setup as you listet.
DSM Dyno Challenge - Highest Horsepower
DSM 1/4 Mile Times - 1/4 ET

Opps sorry i didnt realize that. Thanks for the links though.

 

[donniekak]

You will do good to run a turbo ecu for the knock retard.

 

[carmiencke]

You will do good to run a turbo ecu for the knock retard.

Depending on the deals i come across i will either run a turbo ecu or find something to tune the na ecu. Since your in the valley and do this kind of work whats a good machine shop to go to?

 

[Sp1kE]

The machine shop guy told me even low mileage motors (under 100 000km) can create a taper in the cylinder walls.
And it is almost always suggested to do a bore to get it straight again.
But you always hear of guys just doing a quick hone and new rings....
Choice is yours but I say bore it.